Wednesday, July 13, 2022

3625 - SPACEx SATELLITES - launching like fire works

  -  3625  -  SPACEx SATELLITES  -  launching like fire works?    SpaceX launched 46 satellites and landed the returning rocket on a ship at sea on  July 10, 2022.  A two-stage Falcon 9 rocket topped with 46 of SpaceX's Starlink internet satellites was launched from California's Vandenberg Space Force Base.


-----------------  3625  - SPACEx SATELLITES  -  launching like fire works?

-  About 8.5 minutes after liftoff, the Falcon 9's first stage came back to Earth and landed on the SpaceX droneship which was stationed in the Pacific Ocean.

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-    It was the sixth launch and landing for this Falcon 9 first stage. The booster also helped loft the Earth-observation satellite Sentinel-6 Michael Freilich, NASA's Double Asteroid Redirection Test mission and three Starlink batches.

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-  The Falcon 9's upper stage deployed the 46 Starlink satellites into low Earth orbit 63 minutes after liftoff.  This launch was the 29th orbital mission of the year for SpaceX and the 17th dedicated to Starlink which is the company's huge internet-satellite constellation. 

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-  SpaceX has launched more than 2,750 Starlink satellites to date, and the number will continue to grow for the foreseeable future. The company already has approval to launch 12,000 Starlink craft, and it has applied to an international regulator for permission to loft up to 30,000 more on top of that.

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-  SpaceX's “Starlink” satellites may be used for navigation and global positioning in addition to their core function of “broadband Internet“.

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-  A group of engineering researchers external to SpaceX found a way to use the Starlink constellation signals for navigation similar to the capabilities provided by global positioning satellites (GPS). 

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-  Researchers triangulated the signals from six Starlink satellites to fix upon a location on Earth with less than 27 feet of accuracy. That's comparable to the typical GPS capabilities of a smartphone, which typically pinpoints your spot on Earth to within 16 feet, depending on the conditions.

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-    Even though Starlink wasn't designed for navigation purposes it was possible to learn parts of the system well enough to use it for navigation.  The researchers used the signals from several satellites and developed an algorithm to locate a position on Earth.  ( I have a summary of this math algorithm if you are interested.)

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-  Next, they placed an antenna on the University of California, Irvine campus in an attempt to find its location using Starlink. Their experiment placed the estimated position of the antenna, using Starlink signals, within 25 feet of its actual position.

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-   Other low Earth orbit satellite constellations zeroed in on locations to within about 75 feet. An unrelated project with the U.S. Air Force, to pinpoint locations of high-altitude aircraft, produced an accuracy of 16.5 feet.

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-   Starlink's accuracy, using this methodology, will increase as more satellites in the fleet fly to orbit. SpaceX has about 1,700 working satellites today,  but the company hopes to launch more than 40,000 into orbit.  Recent launches, 2022,  have been delayed due to a liquid oxygen shortage induced by higher medical needs during the COVID-19 pandemic.

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-  The researchers suggested this method of using Starlink navigation could supplement traditional GPS navigation, the latter of which has vulnerabilities. Since GPS has been around for more than 30 years.  It has a well-known signal, it is easy to use on smartphones or vehicles, but also more "vulnerable to attacks".

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-  Starlink also has an advantage with its altitude, orbiting at roughly 750 miles, much closer to Earth than GPS in medium-Earth orbit. Starlink satellites are also launched once every few weeks, typically.   GPS launches are once every few months or years thus allowing Starlink to have more frequent hardware upgrades. 

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-  Coincidentally, in recent years SpaceX has launched several GPS satellites for the U.S. Space Force. Founder Elon Musk has so far offered no comment.

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July 12, 2022          SPACEx SATELLITES  -  launching like fire works?          3625                                                                                                                                        

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